A central processing unit (CPU) socket or CPU slot is a mechanical component that provides mechanical and electrical connections between a microprocessor and a printed circuit board (PCB). This allows the CPU to be replaced without soldering.
Common sockets have retention clips that apply a constant force, which must be overcome when a device is inserted. For chips with a large number of pins, either zero insertion force (ZIF) sockets or land grid array (LGA) sockets are used instead. These designs apply a compression force once either a handle (for ZIF type) or a surface plate (LGA type) is put into place. The surface plate may be referred to as an integrated loading mechanism (ILM). The designs provide superior mechanical retention while avoiding the risk of bending pins when inserting the chip into the socket.
CPU sockets are used in desktop and server computers. As they allow easy swapping of components, they are also used for prototyping new circuits. Laptops typically use surface mount CPUs, which need less space than a socketed part.
A conventional CPU socket is made of plastic, a lever or latch, and metal contacts for each of the pins or lands on the CPU. Many packages are keyed to ensure the proper insertion of the CPU. CPUs with a pin grid array (PGA) package are inserted into the socket and the latch is closed. CPUs with an LGA package are inserted into the socket, the latch plate is flipped into position atop the CPU, and the lever is lowered and locked into place, pressing the CPU's contacts firmly against the socket's lands and ensuring a good connection, as well as increased mechanical stability.
However, improvements are needed in the field of integrated circuit (IC) socket technology, particular for high end microprocessor applications.